1. Field of the Invention
The present invention relates to an image processing apparatus for reading original image data and digitally processing it.
2. Description of the Prior Art
In an image processing apparatus of this type, an original image is converted into an electrical signal by photoelectric conversion. Then, the electrical signal is simultaneously subjected to A/D conversion and shading correction. Upon predetermined processing, the signal is converted into multiple-valued data, e.g., binary data to be used for display or recording. Threshold value data used in this multiple-value conversion is stored in a ROM or the like in the image processing circuit.
In a color image processing apparatus, color image data is read and converted into a plurality of color signals. The color signals are simultaneously subjected to A/D conversion and shading correction. Upon color separation, each color signal is converted into a color signal having a plurality of bits. Then, these signals are subjected to predetermined processing, and converted into multiple-valued data, e.g., binary data to be used for display or recording. A table for the color separation processing described above is stored in a ROM in the image processing apparatus in advance.
However, since each ROM for storing the above-described threshold data or color table is fixed on an internal processing circuit board, when threshold values need be changed or different color separation is required, a corresponding ROM must be replaced with another one.
In order to replace the ROM on the board with another ROM, a housing of the apparatus must be disassembled. For this reason, this replacement operation is limited to a serviceman. Therefore, a user cannot quickly obtain an image with a desired tone or color separation.
A system may be considered, wherein different threshold data or color separation tables are stored in a plurality of ROMs, and one of the ROMs is selected by a switching operation in an operation section. In this case, however, a large ROM capacity (quantity) is required, and it is impossible to include all the data necessary for all the users.
According to the above-described image processing apparatus, a high-speed ROM (e.g., a bipolar ROM) is used to store the threshold value data or the color separation table. Since such a high-speed ROM has a capacity of about 8 Kb, it cannot store a large pattern. Furthermore, since such a ROM has high power consumption, and heat is generated, a countermeasure for solving such a problem is required.
In addition, this image processing apparatus only reads data of an original, applies predetermined processing (edge emphasis, trimming, partial/overall color conversion, and the like) to the data, and directly displays or stores the data. Therefore, when a specific format such as a confidential mark, a graph, or a ruled line need be added to an original, the data of the original must be written on an original with a corresponding format, or the graph or the ruled line must be written (stamped) on the original. For this reason, a plurality of formats must be prepared and managed.